Simulation globale de l'éclairage pour des séquences animées prenant en en compte la cohérence temporelle

Cyrille Damez 1
1 iMAGIS - Models, Algorithms and Geometry for Computer Generated Image Graphics
GRAVIR - IMAG - Graphisme, Vision et Robotique, Inria Grenoble - Rhône-Alpes
Abstract : In image synthesis, the global illumination family of methods rely on the expression of the energetic equilibrium between objects, and as consequence the precise simulation of subtle lighting effects due to numerous reflections of light, that couldn't be taken into account by local lighting models. Therefore, it seems logical to try to use them for the synthesis of realistic computer animations. In this document, we suggest to replace the computation of the numerous integral equations corresponding to each frame by a single 4-dimensional equation. We propose an extension of the hierarchical radiosity algorithm, in the case where all movement is known a priori, that allows us to benefit from the temporal coherence. The radiosity at each point of the scene, for each date of the animation, is expressed in a hierarchical function basis defined over a mesh produced by an automatic refinement process. The extension of this mesh to a 4-dimensional space allows the computation of light exchanges over a finite time interval instead of a given fixed date. This algorithm allows the simulation of global light exchanges in an animated scene, faster and with a quality similar to frame by frame computations.To this purpose, we present new dedicated refinement oracles. To allow the computation of geometrically complex scenes, we discuss the extension of clustering approaches to the case of animated scenes. We also introduce a method to reduce the temporal discontinuities in the radiosity function based on the use of higher order basis functions (MultiWavelets) in the time dimension. Finally, we present a mechanism to schedule the space-time hierarchical radiosity computations to allow the use of disk caching and reduce the amount of memory required by our algorithm.
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Submitted on : Monday, February 16, 2004 - 10:34:55 AM
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Cyrille Damez. Simulation globale de l'éclairage pour des séquences animées prenant en en compte la cohérence temporelle. Interface homme-machine [cs.HC]. Université Joseph-Fourier - Grenoble I, 2001. Français. ⟨tel-00004671⟩

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